One of the problems to be overcome with such speed variators relates to the changing of the belt between the driving and driven sheaves in order to make the operation as easy as possible as well as to facilitate the changing of auxiliary transmission belts connected between the driven sheave and auxiliary devices driven thereby.
Keeping in mind the lack of space usually available around the speed variator sheaves, the changing of the V-belt normally requires the dismounting of the fixed side of at least one of the sheaves, with respect to both the movable side of the sheave and their common shaft.
The remounting of the fixed side may prove difficult because it requires overcoming the biasing force exerted by the resilient biasing means associated with the movable side, and because, where the sheave is the driving sheave, the spring force is relatively high and may be of the order of 150 to 200 kg.